It doesn't really matter if the recordings were legally obtained unless the matter goes before a court. At that point, it is up to the trier to determine if the evidence will be allowed.
Courts have to power to either:
1. reject the evidence on the grounds that the offence committed in obtaining the evidence was not justified in the circumstances; or
2. allow the evidence on the grounds that doing so is in the interests of justice, regardless of the offence committed.
To have the evidence dismissed, you would have to essentially show that:
1. the offence committed in obtaining the evidence is far more serious than the matter before the court; and/or
2. that the evidence could have been obtained without committing the offence.
Before continuing, the statement
"there is currently no law restricting CCTV in a private residential setting" is incorrect. Recording audio or video is covered by the
NSW Surveillance Devices Act.
That said however, the Act does allow for recording audio without consent if doing so is reasonably necessary in order to protect the legal interests of the party making the recording. So basically, if there is a proven history or AVO involved, then the recording would likely be deemed legally obtained.